Corrosion inhibitors and compositions containing the same



, engine.

provide a method gines containing silver Unite CORROSION INHIBITORS ANTS COMPUSHTEONS CONTAINING THE SAli/[E Ellis K. Fields, Chicago, 11]., assignor to Standard Oil Company, Chicago, 11]., a corporation of Indiana No Drawing. Application October 31, 1952, Serial No. 318,091

37 Claims. (Cl. 252==32.'7)

- pounds.

Advances in the design and construction of internal combustion engines to produce improved and more eflicient and economical engines have presented many problems in the lubrication of the modern internal combustion To meet the increased severe demands upon engine lubricants, many types of lubricant additives have been developed to obtain certain desired characteristics thereof. Among the more effective addition agents which have been developed for compounding with lubricants are many sulfur-containing organic compounds, such as by way of example, sulfurized tel'penes, sulfurized hydrocarbon oils, vegetable oils or animal oils, xanthate esters, organic polysulfides, particularly polyalkyl polysulfides, metal salts of organo-substituted thioacids of phosphorus, metal salts of the reaction product of a phosphorus sulfide and a hydrocarbon, such as for example, polybutenes and other polyolefins, and combinations of the foregoing.

Recent increased use of silver and similar metal in the construction of improved internal combustion engines has created new problems in the use of sulfur-containing additives in lubricants for such engines; the primary problem created being the corrosion of such silver parts of the engine by the sulfur-containing additives. While such corrosion can be eliminated by avoiding the use of sulfurcontaining additives in lubricants for such engmes, this solution of the problem is accompanied by the loss of the highly desired beneficial effects of the additives of this 1 e.

It-is an object of the present invention to provide a non-corrosive composition of matter. Another ob ect of the invention is to provide a composition non-corrosive to silver and similar metal. A still further object of the invention is to provide a composition which will inhibit the cornosion of silver and similar metal by sulfur and/or organo sulfur-containing compounds. A still further object of the invention is to provide a lubricant composition which is non-corrosive. Still another object of the invention is to provide a lubricant composition contammg an addition agent which will inhibit the corrosion of silver and similar metal by sulfur and/ or organo sulfur contaming compounds. A further object of the invent on 18 to provide a method of inhibiting the corrosion of silver and similar metal. Still another object of the invention is to of lubricating internal combustion enand similar metal parts and inhibi'ting the corrosion of such metals by lubricants which contain sulfur and/or organo sulfur-contatnmg compounds.

In accordance with the present invention, the new composition of matter is the oil-soluble reaction product of an aldehyde, a mercaptan and 2,5-dimercapto-l,3,4-th1ad1- azole in the molar ratio of from about 222:1 to :2:9, and preferably in the molar 'ratio of 2:211. In general,

' the reaction is carried out by adding an aldehyde to a mixture of the mercaptan and the dimercapto-thiadiazole, and heating the mixture at temperatures of from about 40 C. to about 140 C. for a period of from twenty minutes .to about sixteen hours. Preferably, the reaction is carried out inthe presence of a suitable solvent,

such 8 I 2.73m Patented Mar. 8, 1955 ary.

The aldehyde employed may be an aliphatic, an aromanic, or a heterocyclic aldehyde of from about 1 to about 20 or more carbon atoms, and may contain subst1tuents, such as alkoxy, hydroxy, alkyl mercapto, halogen or mtro groups. Examples of suitable aldehydes are formaldehyde, acetaldehyde, benzaldehyde, Z-ethylhexyl aldehyde, butyraldehyde, heptaldehyde, caprylic aldehyde, acrylicaldehyde, crotonaldehyde, vinyl acetaldehyde, phenyl acetaldehyde, nitrobenzaldehyde, 'salicyaldehyde, furfural, chloral, etc. Any mercaptan can be employed in the reaction although an aliphatic or aromatic monoor poly-mercaptan containing from about 1 to about 30 carbon atoms, and preferably from about 6 to about 20 carbon atoms, is preferred. Examples of suitable mercaptans are ethyl mercaptan, butyl mercaptan, hexyl mercaptan, octyl mercaptan, nonyl mercaptan, octadecyl mercaptan, thiophenol, etc.

The preparation of the above-described reaction roducts is illustrated by the following examples, whic are given by way of illustration and are not intended to limit the scope of the invention.

EXAMPLE I ute period. Stirring was continued at C. for one and one-half hours and the mixture then stripped in vacuo and filtered through cehte. A yield of 143 grams of a viscous yellow product was obtained which analyzed as follows:

Per cent Carbon Hydrogen Sulfur Nitrogen EXAMPLE II Carbon Hydrogen Sulfur Nitrogen EXAMPLE II A mixture of 30 grams (.2 mol.) 2,5-dimercapto-l,3,4- thiadiazole, 58.4 grams (0.4 mols) tertiary octyl mercaptan and 51.2 grams (0.4 mol.) Z-ethylhexaldehyde in 75 cc. dioxane, was heated at C.'for four hours, stripped in vacuo to remove the diluent and the water of reaction, and filtered through celite. 100 grams of a viscous yellow product was obtained. 1

- EXAMPLE -IV A mixture of 45 g. (.3 mole) 2,5-dimercapto-l,3,4-thiadiazole and 102 cc. (.6 mole) t-octyl mercaptan was stirred at 90 C. and treated drop-wise with 61 cc. benzaldehyde over a 35 minute period. The mixture was stirred at 100 C. for 2 hours, stripped in vacuo and filtered through celite plus a little alumina. The product, g., was a very viscous yellow-orange liquid completely soluble in naphtha. The product contained 27.4% sulfur and 4.9% nitrogen.

' cant base oils, such EXAMPLE V 50 cc. of furfural (6 mole) was added, drop-wise, to a mixture of 102 cc. (.6 mole) t-octyl mercaptan and 45 grams (.3 mole) 2,5-dimercapto-1,3,4-thiadiazole and the mixture stirred for two hours at a temperature of 90 C. The reaction product was then stripped in vacuo and filtered'while warm. The product, 120 grains, was a dark purple viscous material having a sulfur content of 25.1%

. and a nitrogen content of 4.4%

and 4 millimeters pressure, then filtered hot through a little celite. The product, 94 g, was a viscous-orange oil. Instead of reacting 2,5-dirnercapto-l,3,4-thiadia2ole with the mercaptan and aldehyde as above described in the preparation of the additive, we may carry out the reaction by forming in situthe dimercaptc-thiadiazole and reacting the same with the aldehyde and mercaptan as illustrated by the following example:

EXAMPLE Vii To a mixture of 150 grams of cracked ice and 130.5 cc. of 84% hydrazine hydrate was added 280 cc. of carbon disulfide over a period of 10 minutes. While cooling the mixture externally, a solution of 180 grams of sodium hydroxide in 325 cc. of water and 30 cc. of ethyl alcohol was added drop-wise to the cooled mixture while maintaining a temperature of about 50 The mixture was then stirred and refluxed at 85 C. for three hours, cooled and acidified with 120 cc. of concentrated sulfuric acid diluted with 200 grams of ice. To the resulting slurry of 2,5-dimercapto-l3. hthiadiazole in sodium sulfate solution was added 1000 cc. of tertiary octyl mercaptan, and then with vigorous agitation was added, drop-wise, 374 cc. of 37% aqueous formaldehyde. The resultant mixture was heated at 85 C. for two hours and cooled to room temperature (about 23 C.). The mixture separated into a lower solidified layer of sodium sulfate and an upper liquid layer. The latter was decanted, treated with 10 grams of sodium bicarbonate, then stripped in vacuo. and filtered through celite; 610 grams of a light yellow liquid product was obtained.

The abov -described reaction products are effective .corrosion, inhibitors, particularly with respect to silver and similar metals when used in combination with lubrias hydrocarbon oils, synthetic hydrocarbon oils, such as those obtained by the polymerization of hydrocarbons, such as olefin polymers, for example, polybutenes. polypropylene and mixtures thereof, etc.; synthetic lubricating oils of the allcylene-oxide type, for example, the "Ucon oils. marketed by Carbide and Carbon Corporation. as well as other synthetic oils. such as the polvcarboxylic acid ester type oils, such as the esters of adipic acid, sebacic'acid, maleic acid, azelaic acid. etc. The herein-described reaction products are effectively used in such lubricants in concentrations of from about 0.02% to about 10%, and preferably from about 0.05% to about 5%.

While the above-described reaction products can be suitably employed alone in combination with a base oil, they are usually used in combination with other lubricant addition agents, which impart various desired characteristics to the base oil. Usually, these reaction products are used in conjunction with detergent-tvpe additives. particularly those which contain sulfur or phos horus and sulfur. The additives of this type are usually used in amounts of from about 0.002% to about 10%. and preferably. from about 0.01% to about 5%. Among the phosphorus and sulfur-containing addition agents are the neutralized reaction products of a phosphorus sulfide, and a hydrocarbon, ester. Of the phosphorus sulfide reaction product additives, we prefer to employ the neutralized reaction products of a phosphorus sulfide. such as phosphorus pentasulfide. and a hydrocarbon of the type described in U. S. 2,316,082 issued to C. I As taught in this patent, the preferred hydrocarbon constituent of the reaction is a mono-olefin hydrocarbon polymer resulting from the polymerization of low molecular weight mono-olefin hydrocarbons, such as propyl- C. or lower.

an alcohol and a ltetone, an amine or an M. Loane et 231., April 6, 1943.

polymers may be obtained by the polymerization of v mono-olefins of less than 6 carbon atoms in the presence of a catalyst, such as sulfuric acid, phosphoric acid, boron fluoride, aluminum chloride, or other similar halide catalysts of the Fricdel-Crafts type.

The polymers employed are preferably mono-olefin polymers or mixtures of monoolefin polymers and iso mono-olefin polymers having molecular weights ranging from about 150 to about 50,000, or more, and preferably from about 500 to about 10,000. Such polymers can be obtained, for example, by the polymerization in the liquid phase of a hydrocarbon mixture containing monoolefins and isomono-olefins, such as butylene and isobutylene at a temperature of from about 80 F. to about 100 F. inthe presence of a metal halide catalyst of the Frredcl-Crafts type, such as for example, boron fluoride, aluminum chloride, and the like. In the preparation of these polymers, a hydrocarbon mixture containing isobutylene, butylenes and butanes recovered from petroleum gases especially those gases produced in the crack- Lug ogipetroleum oils in the manufacture of gasoline can e us izing in the liquid phase a hydrocarbon mixture comprising substantially C3 hydrocarbons in the presence of an aluminum chloride-complex catalyst. The catalyst is preferably prepared by heating aluminum chloride with isooctane. The hydrocarbon mixture is introduced into the bottom of the reactor and passed upwardly through the catalyst layer, while a temperature of from about 50 F. to about 110 F. is maintained in the reactor. The propane and other saturated gases pass through the catalyst while the propylene is polymerized under these conditions. The propylene polymer can be fractionated to any desired molecular weight, preferably from about 500 to about 1000 or higher.

Other suitable polymers are those obtained by polymerizing a hydrocarbon mixture containing about 10% to about 25% isobutylene at a temperature of from about 0 F. to about 100 F., and preferably 0 F. to about 32 F. in the presence of boron fluoride. After the polymerization of the isobutylene together with a relatively minor amount of the normal olefins present, the reaction mass is neutralized, washed free of acidic substances and the unreacted hydrocarbons subsequently separated from the polymers by distillation. The polymer mixture so obtained, depending upon the temperature of reaction, varies in consistency from a light liquid to viscous oily material and contains polymers having molecular weights ranging from about 100 to about 2000, or higher. The polymers so obtained may be used as such, or the polymer may be fractionated under reduced pressure into.

' of anhydrous inorganic halides, such as aluminum chloride, zinc chloride, boron fluoride, and the like.

Examples of other high molecular weight olefinic hydrocarbons, which can be employed, are. cetene (Cm), cerotene (C20), melene (Can), and mixed high molecular weight alkenes obtained by cracking petroleum oils.

Other preferred olefins suitable for the preparation of the phosphorus sulfide reaction products are olefins having at least 20 carbon atoms in the molecule of which from about 13 carbon atoms to about 18 carbon atoms, and preferably at least 15 carbon atoms are in a long can be obtained by the dehydrogenation of paraflins, such as by cracking of paraffin waxes or by the dehalogenation of alkyl halides, preferably long chain alkyl halides, particularly halogenated paraflin waxes.

As a starting material there can be used the polymer the presence of aluminum etc.

escapes Nos. 1,955,260, 1,970,402 and 2,131,398. Still another type of olefin polymer which may be employed is the polymer resulting from the treatment or vapor phase cracked gasoline and/or gasoline fractions with sulfuric acid or solid adsorbents, such as fullcrs earth, whereby unsaturated polymerized hydrocarbons are removed. The reaction products of the phosphorus sulfide and the polymers resulting from the volatilization of hydrocarbons as described, for example, in United States Patents Nos. 2,197,768 and 2,191,787 are also suitable.

' Other hydrocarbons that can be reacted with a phosphorus sulfide are aromatic hydrocarbons, such as for example, benzene, naphthalene, toluene, xylene, diphcuyl, and the like, or with an alkylatecl aromatic hydrocarbon, such as for example, benzene having an alkyl substituent having at least four carbon atoms, and "mainly at least eight carbon atoms, such as a long chain parafiin The phosphorus sulfidehydrocarbon reaction product can be readily obtained by reacting a phosphorus sulfide, for example, P255 with the hydrocarbon at a temperature of from about 200 F. to about 500 F., and preferably from about 200 F. to about 400 F., using from about 1% to about 50%, and preferably from about 5% to about- 25% of the phosphorus sulfide in the reaction. it is advantageous to maintain a non-oxidizing atmosphere, such as for example, an atmosphere of nitrogen above the reaction mixture. Usually, it is preferable to use an amount of the phosphorus sulfide that will completely react with the hydrocarbon so that no further purification becomes necessary; however, excess amount of phosphorus sulfide can be used and separated from the product by filtration or by dilution with a hydrocarbon solvent, such as hexane, filtering and subsequently removing the solvent by suitable means, such as by distillation. If desired, the reaction product can be further treated with steam at an elevated temperature of from about 100 F. to about 600 F.

The phosphorus sulfide-hydrocarbon reaction product normally shows a titratable acidity which is neutralized by treatment with a basic reagent. The phosphorus sulfide-hydrocarbon reaction product, when neutrahzed with a basic reagent, containing a metal constituent, is characterized by the presence or retention of the metal constituent of the basic reagent.

The neutralized phosphorus sulfide-hydrocarbon reaction product can be obtained by treating the acidic reaction product with a suitable basic compound, such as hydroxide, carbonate, oxide or sulfide of an alkahne earth metal or an alkali metal, such as for example, potassium hydroxide, sodium hydroxide, sodium sulfide, calcium oxide, lime, barium hydroxide, barium oxide,

ample, ammonia or an alkyl or aryl-substituted ammonia, such as amines. The neutralization of the "phosphorus sulfide-hydrocarbon reaction product is carried out preferably in a non-oxidizing atmosphere by contacting the acidic reaction product either as such or dissolved in a suitable solvent, such as naphtha "with a solution of the basic agent. As an alternative method, the reaction product can be treated with solid alkaline compounds, such as KOH, NaOH, NazCOs, KzCOs, CaO, BaO, Ba(OH)z, NazS, and the like, at an elevated temperature of from about 100 F. to about 600 F. Neutralized reaction products containing a heavy metal constrtpent such as for example, tin, titanium, aluminum, chromium, cobalt, zinc, iron, and the like, can be obtained by reacting a salt of the desired heavy metal with the phosphorus sulfide-hydrocarbon reaction product which has been treated with the phosphorus sulfide-hydrocarbon reaction product, which has been treated with a basic reagent, such as above described.

Other phosphorus sulfide-reaction products which can be used are the reaction products of a phosphorus sulfide and a fatty acid ester of the type described in U. S.

2,399,243; the phosphorus sulfidc-dcgras reaction products of U. S. 2,413,332; the reaction product of an alkylated phenol with the condensation product of P285 and turpentine of U. ,8. 2,409,877 and U. S. 2,409,878; the

reaction product of a phosphorus sulfide and stearonitrile of U. S. 2,416,807; etc.

The silver corrosion inhibiting property of the abovedescribed dimercapto-thiadiazole reaction products is demonstrated by the data in Table i, which were obtained Other basic reagents can be used, such as for exs by subjecting mixtures of hydrocarbon oil, a neutralized rcactionproduct of Pz S5 and a polybutene, and various 2,5-dnnercapto 1,3,4-th1adiazole reaction products to the one end for suspension, is lightly abraided with No. 0 steel wool, wiped free of any adhering steel Wool, washed with carbon tetrachloride, air-dried and then weighed to 0.1 milligram. 300 cc. of the oil to be tested is placed in a 500 cc. lipless glass beaker and the oil heated to a tcmpcratm'cof 300 F. (12 F.) and the silver test strip suspended in the oil so that the strip is completely 1mmersed therein. The oil in the beaker is stirred by means of a glass stirrer operating at 300 R. P. M. At the end of twenty-four hours, the silver strip is removed, and while still hot, rinsed thoroughly with-carbon tetrachloride and air-dried. The appearance of the strip is then visually noted and given ratings according to the following scale:

1Bright 2-Stained 3-Grey-black 4-Black, smooth 5Black, flake After the visual inspection, the silver strip is immersed in 'an 10% potassium cyanide solution at room temperature until the silver surface assumes its original bright or silver appearance. The silver strip is then washed successively with distilled water and acetone, air-dried and weighed.

The following lubricant compositions were subjected to the above test and the results obtained tabulated in Table I.

Sample A.Control (solvent extracted SAE 30 oil+ 3.3% barium-containing neutralized reaction product of P285 and a polybutene of about 1000 molecular weight).

Sample B.A+0.75% reaction product of Example 1.

Sample C. -A+0.75% reaction product of Example II.

ISample D.-'A+0.75% reaction product of Example lSzlzznple E.A+0.75% reaction product of Examp e Sample F.A+0.75% reaction product of Example V.

Sample G.-A+0.75% reaction product of Example VII.

Table 1 Silver Cor- Sample Since a weight loss of 20 milligrams is allowable, the ability of the 2,5-dimercapto-1,3,4-thiadiazole derivatives of this invention to inhibit silver corrosion is demonstrated by the above data.

The effectiveness of the herein-described dimercaptothiadiazole reaction products in inhibiting corrosion of copper and/or lead-containing metals, such as for example, copper-lead alloys, is demonstrated by the data in Table II, obtained by subjecting lubricants containing the additive to the following test:

A copper-lead test specimen is lightly abraided with steel wool, washed with naphtha, dried and weighed to the nearest milligram. The cleaned copper-lead test specimen is suspended in a steel beaker, cleaned with a hot trisodium phosphate solution, rinsed with water, acetone and dried, and 250 grams of the oil to be tested, together with 0.625 gram lead oxide and 50 grams of a 30-35 mesh sand charged to the beaker. The beaker is then placed in a bath or heating block and heated to a temperature of 300 (i2 F.), while the contents are stirred by meansof a stirrer rotating at 750 R. P. M. The contents of the beaker are maintained at this temperature for twenty-four hours, after which the copperlead test specimen is removed, rinsed with naphtha, dried with oth a test specimen is then re laced in the beaker and an additional 0.375 grams lead oxide added to the test oil. At the end of an additional twen four hours of test operation, the test specimen is again removed, rinsed and dried as before, and weighed. The test specimen is again placed in the beaker together with an additional 0.250 grams of lead oxid continued for another twe hours total). At th specimen is removed from th dried and weighed.

The loss in weigh after each weighing. g

This test, known the Sand Stirring Corrosion Test, is referred to hereinafter S k f The data obtained when subjecting lubricant compositions, designated Samples A to E and G, above, to the foregoing test, are tabulated in Table II.

and weified. Th

1': of test specimen is recorded grams in 48 hours and 500 grams in 72 hours are allowable, the corrosion inhibiting property of the herein-described 2,5-dimercapto- 1,3,4-thiadiazole derivatives is clearly demonstrated by the above data.

Under certain conditions, it is desirable to use In Iubricant compositions from about 0.01% to about and preferably from about 0.1% to about 2%, elemental sulfur or an organic sulfur-containing compound of the type hereinabove described, either alone or in combination er additives. Effective lubricant compositions are obtained by the combination of the neutralized reaction products of a phosphorus sulfide and a hydrocarbon, as above described, with elemental sulfur or an organic sulfur-containing compound, such as sulfurized mineral oils, sulfurized non-drying animal and vegetable oils, sulfurized olefins and olefin polymers, sulfurized sperm oil,

Since weight losses of 200 milli H. Rogers et al. While these compounds mpart highly desired characteristics to lubricants, and efiectively' inhibit the corrosion of copper and/or lead, they are corrosive to silver and similar metals, and for this reason, lubricants containing suc ts fail to pass the above-described E.M;D rdance with the oration in such present invention, however, the incorp small amounts, namely from lubricant compositions of about 0.1% to about and preferably from about 0.25% to about 5% of the herein-described 2,5-dimercapto-1,3,4-thiadiazole reaction products, effectively inhibits the corrosiveness of the silver corrosive compounds without impairing their other desired properties.

The ability of the herein-described 2,5-dimercapto- 1,3,4-thiadiazole derivatives to inhibit the silver corrosion tendency of active sulfur-containing organic compounds is demonstrated by the following E. M. D. 'data in Table III, obtained with the following compositionsz' Sample A'.-(Control).Solvent extracted SAE-SO mineral oil+3.3% barium-containing neutralized reaction product of P285 and a polybutene of about 1000 molecular weight+0.75% sulfurized dipentene.

Sample B'.-A'+0.10% product of Example I,

Sample C'.A'+0.l5% product of Example I,

Sample D'.A'+0.15% product of Example II,

Sample E.A+0.15 product of Ex Sample F .A+0.l5 product of Example IV, supra.

Sample G'.-A+0.15% product of Example V, supra. Sample H'.A'+0.15% product of Example VII, supra.

supra. supra. supra. ample III, supra.

5 reference to Sample dlazole derivatives in sired properti hydrocarb IV.

g hydrocarbon oils to as the I. S. 0.. T be tested are glass beaker -copper and rods of 6 is stirred stirrer.

es thereto, such as in on 011s as demonstrated ese data were obtained by contamlng various above'de OWLDg oxidation test herein 1 this test 250 cc. of the heated at 330 F. to 332 F. in a in th 5 square millime 3:10 (slguare millimeters gfdiron. Fou ,mi lame er are su en e in the oil at about 1300 R P Sp the oxidation of data in Table in tabulatedinTable IV. ilSample A".-(Control).-Solvent extracted SA 0 Sample B".A"+0.5% of the product of Exar Sample C".A"+1.0% of the product of Exam Table I Naphtha, Insoluble Sample 24hrs. 72hrs. 241118. 48hrs. 72hrs Bx 3. 36 o'CIIIIIIII 1 genes st be inhibited. nless otherwise stated, percentages given herein in the appended claims are weight percentages.

Soluble oil compositions containing the herein dew and claimed reaction products of an aldehyde, a men dlmercapto-1,3,4-thiadiazole are claime application Serial No. 339

copending Roberts et al the present invention has been February 27, 1953. Although specific preferred embodrm described ents thereof,

invention is not to be considered as limited thereto but includes within its scope such modifications and variations as coilne within the spirit of tl: appended claims.

c mm:

1. A new composition of matter, the reaction product of an aldehyde, a mercaptan selected from the class consisting of an aliphatic mercaptan and an aromatic mercaptanand 2,5-dimercapto-1,3,4-thiadiazole, said reaction product having corrosion inhibiting properties and being suitable for addition to oils to impart corrosion inhibiting characteristics thereto, said aldehyde, mercaptan and 2,5-dimercapto-2,3,4-thiadiazole being reacted in the molar ratio of from about 2:2:1, respectively, to about 10:2:9, respectively.

2. A composition of matter as described in claim 1 in which the aldehyde is an aliphatic aldehyde of from 1 to about 20 carbon atoms.

3. A composition of matter as described in claim 2 in which the aliphatic aldehyde is formaldehyde.

4. A composition of matter as described in claim 2 in which the aliphatic aldehyde is Z-ethyl hexaldehyde.

5. A new composition of matter as described in claim 1 in which the aldehyde is an aromatic aldehyde.

6. A new composition of matter as described in claim 5 in which the aromatic aldehyde is benzaldehyde.

7. A new composition of matter as described in claim 5 in which the aromatic aldehyde is salicyaidehyde.

8. A new composition of matter as described in claim 1 in which the aldehyde is a heterocyclic aldehyde.

9. A new composition of matter as described in claim 8 in which the heterocyclic aldehyde is furfural;

10. A new composition of matter as described in claim I in which the mercaptan is octyl mercaptan.

11. A new composition of matter as described in claim 1 in which the mercaptan is dodecyi mercaptan.

12. A new composition of matter as described in claim 1 in which the mercaptan is thiophenol.

13. A composition comprising a. major proportion of an oleaginous compound and from about 0.02% to about 10% of a reaction product of an aldehyde, a mercaptan selected from the class consisting of an aliphatic mercaptan and an aromatic mercaptan, and 2,Sdimercapto-1,3,4- thiadiazole, said aldehyde, mercaptan and 2,5-dimercapto- 1,3,4-thiadiazole being reacted in the molar ratio of from about 2:2:1, respectively, to about 10:2:9, respectively.

14. A composition as described in claim 13 in which the aldehyde is an aliphatic aldehyde of from 1 to about carbon atoms.

15. A composition as described in claim 14 in which the aldehyde is formaldehyde.

16. A composition as described in claim the aldehyde is 2-ethyl hexaldehyde.

17. A composition as described in claim the aldehyde is an aromatic aldehyde.

18. A composition as described in claim the aromatic aldehyde is benzaldehyde.

19. A composition as described in claim the aldehyde is a heterocyclic aldehyde.

20. A composition as described in claim the aldehyde is furfural.

21. A composition as described in claim the mercaptan is octylmercaptan.

22. A composition as described in claim 13 in which the mercaptan is dodecyl mercaptan.

23. A composition as described in claim 13 in which the mercaptan is thiophenol.

24. A composition comprising a ma or proportion of an oleaginous compound, from about 0.02% to about 10% of the reaction product of an aldehyde, an aliphatic mercaptan having from 1 to about 30 carbon atoms, and 2,5-dimercapto-1,3,4-thiadiazole in the molar ratio of from about 2:2:1 respectively-to 10:2:9 respectively, and from about 0.001% to about 10% of a sulfur-containing organic compound normally corresive to silver.

25. A- composition as described in claim 24 in which the sulfur-containing organic compound is a s 14 in which 17 in which 13 in which 19 in which 13 in which ne. '26. A lubricant composition comprising a major propor- 13 in whichtype lubricant additive is an alkali tion of an oleaginous compound, from about 0.02% to about 10% of the reaction product of an aldehyde, an aliphatic mercaptan and from about 1 to about 30 carbon atoms, and 2,5-dimercapto-1,3,4-thiadiazole in the molar ratio of from about -2:2:1 to 10:2:9 and from about 0.001% to about 10% of a phosphorus and sulfur-containing detergent-type lubricant additive.

27. A lubricant composition as described in claim 26 in which the phosphorus and sulfur-containing detergenttype lubricant additive is a neutra ed reaction product or a phosphorus sulfide and a hydrocarbon.

28. A lubricant composition as described-in claim 26 lfl WhiCh the phosphorus and sulfur-containing detergentmetal-containing neutralized reaction product of a phosphorus sulfide and an olefin polymer. 29. A lubricant composition as described in claim 26 in which the phosphorus and sulfur-containing lubricant additive is'a potassium-containing neutralized reaction sulfide and an olefin polymer. 30. A lubricant composition as described in claim 26 product of a phosphorus in which the phosphorus and sulfur-containing detergenttype lubricant additive is an alkaline-earth-containing neutralized reaction product of a phosphorus sulfide and an olefin polymer.

I 31. A lubricant composition described in claim 26 in which the phosphorus and sulfur-containing detergenttype lubricant additive is a barium-containing neutralized reaction product of a phosphorus sulfide .and an olefin polymer.

32. A method of inhibiting the corrosion of silver by- 33. A composition comprising a major proportion of an oleaginous compound and from about 0.02% to about 10% of the reaction product dodecyl mercaptan, and 2,S-dimercapto-1,3,4-thiadiazole, said reactants being employed in the molar ratio of from about 2:2:1, respectively, to about 10:2:9 respectively.

of formaldehyde, tertiary 34. A composition comprising a major proportion oi.

anoleaginouscompound and from about 0.02% to about 10% of the reaction product of ethyl hexaldehyde, tertiary octyl mercaptan, and 2,5-dimercapto-1,3,4-thiadiazole, said reactants being employed in the molar ratio of from about 2:2:1, respectively, to about 10:2:9, respectively.

35. A composition comprising a major proportion of an oleaginous compound and from about 0.02% to'about 10% or the reaction product of benzaldehyde, tertiary octyl mercaptan, and 2,5-dimercapto-1,3,4-thiadiazole, said reactants being employed in the molar ratio of from about 2:2:1, respectively, to about 10:2:9, respectively.

36. A composition comprising a major proportion of an oleaginous compound and from about 0.02% to about or the reaction product of furfural, tertiary octyl mercaptan, and 2,5-dimercapto-1,3,4-thiadiazole, said reactants being employed in the molar ratio of from about 2:2:1, respectively, to about 10:2:9, respectively.

37. A composition comprising a major proportion of an oleaginous compound and from about 0.02% to about 10% ot' the reaction product of heptaldehyde, thiophenol, and 2,5-dimercapto-1,3,4-thiadiazole, said reactants being employed in the molar ratio of from about 2:2: 1, respectively, to about 10:2:9, respectively.

References Cited in the file of this patent UNITED STATES PATENTS 2,414,257 Evans et al. Jan. 14, 1947 2,515,318 Schoene July 13, 1950 2,607,737 Woodrufi et a1. Aug. 19, 1952 

1. A NEW COMPOSITION OF MATTER, THE REACTION PRODUCT OF AN ALDEHYDE, A MERCAPTAN SELECTED FROM THE CLASS CONSISTING OF AN ALIPHATIC MERCAPTAN AND AN AROMATIC MERCAPTAN AND 2,5-DIMERCAPTO-1,3,4-THIADIAZOLE, SAID REACTION PRODUCT HAVING CORROSION INHIBITING PROPERTIES AND BEING SUITABLE FOR ADDITION TO OILS TO IMPART CORROSION INHIBITING CHARACTERISTICS THERETO, SAID ALDEHYDE, MERCAPTAN AND 2,5-DIMERCAPTO-2,3,4-THIADIAZOLE BEING REACTED IN THE MOLAR RATIO OF FROM ABOUT 2:2:1, RESPECTIVELY, TO ABOUT 10:2:9, RESPECTIVELY. 